retagged by
12,636 views
13 votes
13 votes

In the context of operating systems, which of the following statements is/are correct with respect to paging?

  1. Paging helps solve the issue of external fragmentation
  2. Page size has no impact on internal fragmentation
  3. Paging incurs memory overheads
  4. Multi-level paging is necessary to support pages of different sizes
retagged by

3 Answers

Best answer
11 votes
11 votes

Pages are divided into fixed size slots , so no external fragmentation

But applications smaller than page size cause internal fragmentation

Page tables take extra pages in memory. Therefore incur extra cost

Correct ans A and C

selected by
20 votes
20 votes
  1. Pages are of fixed size and hence causes no external fragmentation. So, option A is TRUE.
  2. When the required amount of memory for a process is not an exact multiple of page size, internal fragmentation happens. So, option B is FALSE.
  3. Paging requires all the pagetables in use to be in main memory which causes memory overhead. So, option C is TRUE.
  4. This is slightly debatable. Typically a system allows only pages of a fixed size but $\textsf{x86}$ allows Huge pages or even $\textsf{Transparent Huge Pages}$ of size even $1\;\text{GB}$ (typically $2\;\text{MB})$ which can drastically increase the $\text{TLB}$ hit rate for processes needing large amount of memory. And this usage of multiple size of pages is typically handled using multi-level paging. Since there is no strict requirement of multiple levels of page tables to support multiple page sizes (though its not theoretically required I do not know of any such system) this option is FALSE due to the presence of “necessary”

Correct Answer: A;C.

4 votes
4 votes
  • Paging is the technique of non contiguous allocation of physical memory which solves external fragmentation.
  • Paging may cause internal fragmentation depends on the page size and process size in last page, if page size is larger and process size is smaller.
  • Implementation of Paging requires management of Page tables which resides in pages and hence consume additional memory.
  • Multilevel paging is required when size of page table exceeds the size of page. Since page table reside in page, it is further divided to pages of same size. 

With these reasoning $A$ and $C$ is correct 

Answer:

Related questions

18 votes
18 votes
4 answers
1
Arjun asked Feb 18, 2021
10,529 views
Which of the following standard $C$ library functions will always invoke a system call when executed from a single-threaded process in a $\text{UNIX/Linux}$ operating sys...